1. Field of the Invention
This invention relates to apparatus for checking persons for radioactive contamination, comprising detector panels, which are optionally divided in height and extend at an angle to each other and define a room, which is adapted to be occupied by a person to be checked.
2. Description of the Prior Art
In such contamination check chambers, the front and rear sides of a person are sensed and it is difficult to ensure that the measurements are taken at equal distances. When the measurements are taken in two positions of the person, the distances will be small and the sensitivity will be high.
It is known to provide contamination check chambers having lateral entrance and exit doors, which are also provided with detectors. Such chambers may be provided on the floor with detectors in areas on which the feet are to be placed.
Known apparatus for monitoring passenger traffic comprise a check chamber provided with two doors which are so controlled that after one door has been opened the other door cannot be opened when a contamination has been detected.
In a known arrangement, at least three detector panels are arranged at an angle to each other in a top plan view. In such top plan view, two panels extend on opposite sides of a middle panel at an angle of an order of about 135.degree.. Such a checking apparatus may be accommodated in a niche and may closely confine a person to be checked. But a disadvantage resides in that the measurements are taken at large distances at the corners formed between the outer detector panels, which extend at an angle to each other, and the middle detector panel. In said known arrangement the position of the person to be checked is not defined because there are only hand boxes for receiving the hands at the outer edges of the outer panels. Because the elbows may be bent at various angles, which may be large if the upper arms are retracted, and the arms may be bent at the elbow joints, the distances from different persons to be checked to the detector panels defining the niche will vary. The measurements taken on the front and rear sides of a person will not be consistent.
It is also known to provide counting boxes laterally of a chamber-defining wall and to use said boxes for a checking of the hands with photodetectors which permit an entrance of the hands into the boxes. The walls defining such chambers contain detectors, which are described as large-area counters and are separated only by a horizontal blank strip rather than by a vertical blank strip.
In the use of the known arrangements, the results of the measurements taken on the front and rear sides of a person are not consistent with each other and the fact that the arms can be bent to various degrees results in an undefined basic position of the person being checked.
It is an object of the invention to provide an apparatus which is of the kind described first hereinbefore and comprises panels extending at an angle to each other and fewer detectors and which permits more accurate results to be obtained with a simpler arrangement.
That object is obtained in accordance with the invention in that only two detector panels are provided, which extend at an angle to each other, and the detectors carried by each of said panels are separated from each other by a vertical blank strip, which is disposed in a central region of the width of the panel and with reference to the contour of a reference figure in a top plan view is so arranged that the signals generated from the detector means separated by the blank strip can be processed to compensate the influence of the closest approximation of the reference figure to the detector panels in said central region on the generation of said signals.
The two detector panels are provided on one side with detectors or radiation-sensitive detector fields and both detector panels are connected to each other to extend at an angle to each other which has an apex that defines a vertical axis. The two surfaces on which the detector panels are provided with detectors or detector fields face the angular space which is included by the detector panels. Adjacent detectors of each detector panel are separated by a vertical blank strip so that adjacent detectors or detector fields are horizontally spaced apart. With reference to the contour of a reference figure in a top plan view that blank strip is so arranged that said blank strip extends in the area in which the panel is closest to the contour of the reference figure. In the processing of the detector signals the differences between signals from the groups of detectors or detector fields separated by the blank strip will compensate the influence which is due to the approximation to the reference figure.
Such an apparatus requires fewer detectors and has a simpler arrangement than the known apparatus having a comparable measuring range. Because the number of detector panels is small, the gaps obtained in the horizontal measuring configuration will be smaller so that a more accurate result can be obtained with a simpler configuration. The proposed division of the detectors into groups also reduces the zero effect. An essential advantage resides in that the peak sensitivity obtained in the middle of the width of the detector is not disproportionally high in comparison to the sensitivity in the remaining regions so that a rather uniform sensitivity profile can be obtained with only two detector panels.
It will be particularly desirable so to arrange the two detector panels that their sensing surfaces include an angle between 90.degree. and 118.degree.. With an angle of that order of magnitude, the apparatus can well be adapted to various reference figures. In a desirable embodiment, the sensing surfaces of the two detector panels include an angle between 96 and 112 degrees.
In an optimum embodiment, the apparatus is designed for an elliptical reference figure having in a top plan view a major axis of 35 cm and a girth of 95 cm (ICRP) and comprises two detector panels having sensing surfaces which include an angle of an order of 104.degree..
From the explanations given hereinbefore it is apparent that the arrangement in accordance with the invention is selected in consideration of the reference figure and, in particular, the angle and the exact location of the vertical blank strip of each detector panel, which blank strip is particularly disposed in the central region of the width of the panel, must be selected in dependence on the reference figure so that the blank strip which separates adjacent detectors from each other is disposed as closely as possible to the area in which the sensing surface most closely approximates the person to be checked.
In a desirable embodiment the vertical blank strip is arranged in a central region of the width of the detector panel.
If two detector panels extending at an angle to each other are provided each with a planar sensing surface, the angular arrangement in consideration of the reference figure is a special feature and the division of the detectors into two functional groups, which are horizontally spaced apart in the central region of the width of the panel, is of special significance.
Whereas the reference figure is a datum, said datum may be different in different geographic regions so that an adaptation will be desirable.
To permit a complete check of a person, a tread surface provided with a foot detector structure including two detector units for respective feet is arranged in the area defined by the panels. Such a divided detector structure having two units, which form a tread surface, will determine the position to be assumed by the person to be checked.
In a preferred embodiment of the invention, each detector panel is provided on each side of the vertical blank strip with a plurality of vertically spaced apart detectors and an underarm box is provided near the outer edge of detectors mounted on the detector panel and is disposed on a selected level above the tread surface.
In the preferred embodiment described above, each underarm box comprises at least one surface-type detector, which extends over the average length of an underarm and of a hand and at an angle to the plane that is defined by the detectors on the detector panel. In a desirable embodiment, each underarm box includes at least two surface-type detectors.
The longitudinal axis of each underarm box is upwardly inclined relative to the horizontal from an entrance opening of the underarm box to the opposite end of the underarm box.
The provision of such underarm boxes is a particularly desirable feature of this invention. It has already been known to provide hand boxes, which contain short receiving chambers having substantially the length of a hand. Said hand boxes were disposed outside of detector panels of a detecting apparatus and receive the hands of a person to be checked. In that case a person who has inserted his or her hands into the hand boxes can still move his or her wrist, elbow and shoulder joints connecting the hands to the trunk of the person so that the position of the person will not be defined.
Because the hands as well as the underarms are required to be inserted into underarm boxes, the position of a person being checked cannot be changed by a movement that is permitted by the wrist joints. Because the underarms and the hands are constrained to extend in a predetermined direction, any contamination of the underarms can be detected much more reliably and the remaining joints of the arm will substantially be constrained to assume a predetermined position. As a result, a person to be checked will be constrained to assume a position which permits a more reliable check.
This will also be the case when the person to be checked has turned around and his or her underarms no longer extend in the underarm boxes. Such person has previously been compelled to assume a predetermined position by the special arrangement and direction of the underarm boxes and when such person has turned around while standing on the foot detector structure such person will tend to more or less remain in the position assumed by him or her before turning around.
The upward inclination of the underarm boxes will facilitate the insertion of the underarms into the boxes. If two detectors are provided in each underarm box, the transverse axes of such detectors are suitably horizontally arranged.
For a checking of persons differing in height, each person is caused to spontaneously assume a position which is suitable for a check. In embodiments which have been described hereinbefore, this will be accomplished in a particularly desirable manner if the longitudinal center line of each underarm box is upwardly inclined at an angle of about 30.degree. from the entrance opening of an underarm box and said entrance opening is spaced about 130 cm above a tread surface provided with the foot detector. In such an arrangement, persons having a height between 150 and 200 cm can be caused to assume an optimum position and can be optimally checked.
The underarm boxes suitably have a length of about 50 cm. They may extend substantially parallel to each other in a top plan view. In a preferred embodiment, the center lines of the underarm boxes and/or the longitudinal axes of the detectors in the underarm boxes are upwardly inclined from the entrance opening of the underarm box as far as to the opposite end thereof and said detectors converge toward their opposite ends.
In a special embodiment, each underarm box comprises three elongate detectors, which constitute a triangular array in a cross-sectional plane which is normal to a longitudinal axis of the underarm box.
In all embodiments, the adequate insertion of the underarms into the underarm boxes can be checked by suitable sensors. It has surprisingly been found that in such case the constraint of the underarms will cause the person being checked to spontaneously assume a predetermined position, which substantially agrees with the optimum position. A particularly desirable result will be obtained with simple, economical means in the embodiment comprising only two detector panels, which extend at an angle to each other.
It has been explained hereinbefore that in desirable embodiments of the invention the location of the central vertical blank strip can be adjusted in consideration of the figure of the person to be checked. An embodiment which is preferred in this respect is so designed that the angle included by the two detector panels having a vertical blank strip substantially in the central region of their width can be adjusted in dependence on the configuration of a reference figure and for this purpose the two detector panels are interconnected by a hinge.
To permit an adjustment of the angles and elevations and for an adaptation to different reference figures, adjusting means are suitably provided at outer edges of the detector panels. In that case the underarm boxes are provided at said outer edges and the adjusting means can be used to adjust the elevation of each underarm box and the angle between the underarm box and the plane which is defined by the detectors of the detector panel.
The angles between each underarm box and the associated detector panel may be adjusted in dependence on the angle which is included by the two detector panels. It has been explained hereinbefore that the selection of that angle is important for certain measurements. In another desirable embodiment the detector panels extending at an angle to each other constitute a rigid unit, which is angularly movable about a vertical axis, and a resetting drive is provided, which is centered on said axis and is adapted to store resetting energy. In one embodiment, that angle can be intentionally changed or a change of that angle is permitted. In another embodiment, set screws are provided for at least temporarily holding the two detector panels in a position in which they extend at a selected angle to each other. For a temporary adaptation, the two panels may be interconnected by ratchet mechanisms, which limit the adjustment, and resetting means may be provided. Such an arrangement will permit an adaptation to different reference figures. Detent or locking means may be provided, which may be mechanical or may be electromechanical and provided with adjusting magnets and such mechanism may be provided with adjusting drive means so that an adaptation to a person to be checked can be affected within predetermined limits.
The above remarks are applicable to embodiments in which the two detector panels are angularly movable toward each other to a predetermined minimum angle as well as to embodiments in which the panels extending at an angle to each other are angularly movable in unison. A plurality of detector panels extending at an angle to each other and preferably arranged in pairs and provided each with detectors on opposite sides may constitute the wings of a revolving door, which is adapted to be locked in position and to be released by suitable means in an arrangement in which the detectors provided on the panels are electrically connected to signal-processing means.
Such revolving door can be walked through by a large number of persons in succession more quickly than has been possible before. In such an arrangement the wings of the revolving door, particularly the detector panels which constitute the wings of such revolving door, are rigidly interconnected.